by Over 2,000 years ago, the Greek historian Herodotus reported a misguided forbidden experiment in which two children were prevented from hearing human speech so that a king could discover the true, unlearned language of humans.
Scientists now know that human language requires social learning and interaction with other humans, a trait shared with several animal languages.
But why should humans and other animals need to learn a language instead of being born with that knowledge like many other animal species?
This question fascinates me and my colleagues and is the basis for our recently published article in the journal Science. As a biologist, I have spent decades studying honey bee communication and its possible evolution.
There are two common answers to why language should be learned or innate.
On the one hand, when learning complex languages, they can often react to local conditions. A second answer is that complex communication is often difficult to establish, even when individuals are born with some knowledge of the right signals.
Given that the way honey bees communicate is quite sophisticated, we decided to examine how they learn these behaviors to answer this language question.
What is a wobble dance?
Amazingly, honey bees possess one of the most complicated examples of non-human communication.
They can tell each other where to find resources like food, water, or nesting sites with a physical “wiggle dance.” This dance conveys the direction, distance, and quality of a resource to the bee’s nestmates.
Essentially, the dancer points the recruits in the right direction and tells them how far to go, repeatedly circling in a figure-eight pattern centered around a wobble run, in which the bee wiggles its belly as it moves forward.
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Dancers are pursued by potential recruits, bees who follow the dancer closely to learn where to go to find the communicated resource.
Longer wobbles communicate longer distances, and the wobble angle communicates direction. For higher quality resources like sweeter nectar, dancers will repeat the wiggle run more often and run back faster after each wiggle run.
make mistakes
This dance is difficult to produce. The dancer doesn’t just run—the dancer moves about one body length per second—while trying to maintain the right wiggle angle and duration.
It’s also usually in total darkness, amid a crowd of jostling bees, and on an irregular surface.
Bees can therefore make three different types of mistakes: pointing in the wrong direction, signaling the wrong distance, or making more mistakes when performing the figure-eight dance pattern — what researchers call disorder mistakes.
The first two bugs make it difficult for recruits to find the posted location. Clutter bugs can make it difficult for recruits to follow the dancer.
Scientists knew that all Apis mellifera bees begin foraging and dancing only with age, and that they follow even experienced dancers before attempting to dance. Could they learn from experienced teachers?
A “forbidden” bee experiment
My colleagues and I thus created isolated experimental colonies of bees that could not observe other wobble dances until they danced themselves.
Like the ancient experiment described by Herodotus, these bees could not observe the dance language because they were all the same age and had no older, more experienced bees to follow.
In contrast, our control colonies contained bees of all ages, allowing younger bees to follow the older, more experienced dancers.
We recorded the first dances of bees living in colonies with both population age profiles.
The bees that could not follow the dances of experienced bees produced dances with significantly more errors in direction, distance, and disorder than the dances of control bees.
We then tested the same bees later when they were experienced foragers. Bees, which had been lacking in teachers, now produced significantly fewer errors of direction and disorder, possibly because they had more practice or learned by eventually following other dancers.
The dances of the older control bees from colonies with teachers remained as good as their first dances.
This finding has shown us that bees are therefore born with some dance knowledge, but they can learn to dance even better by following experienced bees.
This is the first known example of such complex social communication learning in insects and a form of animal culture.
Dance dialects are about distance
A mystery remained for the bees, who lacked dance teachers early on. They could never correct their distance errors. They continued to overshoot and communicate at greater distances than normal.
Why is this interesting for scientists? The answer might lie in how long-distance communications might adapt to local conditions.
There can be significant differences in where food is distributed in different environments. As a result, different honey bee species have evolved distinct “dance dialects,” described as the relationship between distance to a food source and the corresponding wiggle-dance duration.
Interestingly, these dialects vary even within the same honey bee species. Researchers suspect this variation exists because colonies, even of the same species, can live in vastly different environments.
If learning a language is a way of dealing with different environments, then perhaps each colony should have a long-distance dialect tailored to their location, passed from experienced bees to novices.
If so, our individual teacher-deprived bees may never have corrected their distance errors because they themselves acquired a different distance dialect.
Normally, this dialect would be learned by experienced bees, but could potentially change within a generation if their environmental conditions change or if the colony swarms to a new location.
In addition, each colony has a “dance floor,” or the space where bees dance, with complex terrain that the dancers become better at navigating over time, or by following in the footsteps of older dancers.
These ideas have yet to be tested, but provide a basis for future experiments that will examine cultural transmission between older and younger bees.
We believe that this study and future studies will advance our understanding of collective knowledge and language learning in animal societies.
James C. Nieh, associate dean and professor of biology, University of California, San Diego
This article was republished by The Conversation under a Creative Commons license. Read the original article.
